It does not logically follow from the low infection rates outside of China that these extreme measures are not warranted, quite possibly it's the opposite: low infections follow from strong containment measures.
As for comparisons to the Flu, I see this so often and it always misses the point: it's not one or the other, so why would the medical establishment not fight in the extreme to stop many thousands of deaths that would result if another flu-like disease came along? Second, there is an entire industrial complex complete with seasonal ramp up in staffing to deal with Flu season, and we still see non-negligible fatality rates. Without that support network, which again we don't have for COVID-19, how much worse would things be with the flu? So we should all stop using the flu as some type of benchmark for what a reasonable COVID-19 response looks like.